Journal article
Comparison of Crossbridge Dynamics Between Intact and Skinned Myocardium From Ferret Right Ventricles
Circulation research, Vol.68(3), pp.772-781
03/1991
DOI: 10.1161/01.RES.68.3.772
PMID: 1742866
Abstract
This study compares the crossbridge kinetics of intact and skinned preparations from ferret cardiac muscles at 20°C to determine whether skinning causes any alteration in the crossbridge response to an imposed length change. A papillary or trabecular muscle was isolated from the right ventricle, the muscle length adjusted to give the maximum twitch tension (Lmax), and the preparation was subjected to Ba contracture. When steady tension developed, the length of the preparation was perturbed sinusoidally in 19 discrete frequencies, ranging from 0.13 to 135 Hz, and at a small peak-to-peak amplitude (0.25% Lmax). We identified three exponential processes in the sinusoidal force-response to the imposed length oscillation, and these were labeled processes B, C, and D in order of increasing speed. A slow process, A, normally present in fast-twitch skeletal muscles, is very small or absent in cardiac muscles. Process B is an exponential delay, and the muscle produces oscillatory work on the forcing apparatus; processes C and D are exponential advances in which the muscle absorbs work. The preparation was chemically skinned and activated in the presence of (mM) CaEGTA 6 (pCa 4.55), MgATP 5, magnesium propionate 1, and phosphate 1, pH 7.0, with ionic strength adjusted to 200 mM with potassium propionate. We found that the crossbridge kinetics were not altered by the skinning procedure. The apparent rate constants extracted from the sinusoidal analysis were nearly identical in Ba contracture (intact preparation) and in Ca activation (skinned preparation), and the Nyquist plots were similar. Because the rate constants changed sensitively with the substrate (MgATP) concentrations, we concluded that the substrate is adequately supplied during Ba contracture in the intact preparation. Our study demonstrates the compatibility of results obtained from an intact and from a skinned preparation.
Details
- Title: Subtitle
- Comparison of Crossbridge Dynamics Between Intact and Skinned Myocardium From Ferret Right Ventricles
- Creators
- Yasutake Saeki - Department of Physiology (Y.S.), Tsurumi University School of Dental Medicine, Yokohama, Japan, and the Department of Anatomy (M.K., Y.Z.), College of Medicine, University of Iowa, Iowa City, IowaMasataka KawaiYan Zhao
- Resource Type
- Journal article
- Publication Details
- Circulation research, Vol.68(3), pp.772-781
- Publisher
- American Heart Association, Inc
- DOI
- 10.1161/01.RES.68.3.772
- PMID
- 1742866
- ISSN
- 0009-7330
- eISSN
- 1524-4571
- Language
- English
- Date published
- 03/1991
- Academic Unit
- Anatomy and Cell Biology; Internal Medicine
- Record Identifier
- 9984025563702771
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